The Foley catheter has been the prototype of catheters for some thirty years. It is a balloon catheter and consists of a tube formed of rubber, latex, Silastic, silicone and the like with an inflatable balloon at its inner end which is used to keep the catheter within the bladder. It includes a separate tube to inflate and to deflate the balloon. The only modifications over the years have basically been in the improvement of the rubbers, example, Silastic is superior to latex. The disadvantages of the Foley catheter are: (1) trauma to the urethra, that is, semiconscious or irrational people can pull the inflated balloon through the urethra and the balloon will not deflate. (2) The added expense of the extra lumen for inflating and deflating the balloon. (3) The balloon -- may do not work and must be discarded before use and some that work initially later fail. (4) A syringe and sterile water are necessary to fill the balloon which is an extra expense. (5) The balloon can inadvertently be inflated before it reaches the bladder, for example, in the prostatic-urethra. (6) The "puddle phenomonen" -- the tip of the Foley catheter rests above the bottom of the bladder and as a result, there always remains excessive urine in the bladder, a constant source of infection. (7) The balloon deflates by itself and the catheter falls out. (8) The balloon cannot be deflated when in place.
The techniques for deflating a Foley balloon that does not deflate are traumatic in itself; for example, (1) a fine wire can be passed through the balloon lumen to puncture it, (2) a large needle can be passed through the abdominal wall to attempt to hit the balloon and puncture it, or (3) the balloon can be inflated with alcohol until it bursts. This irritates the bladder and leaves behind tiny fragments of rubber. If the patient is not taken to the operating room for removal of the rubber fragments, the fragments can serve as a source of bladder stone formation and infection.
For a history of the early development of the balloon catheter, reference is made to Urology, January, 1973, Volume I, No. 1, pages 75 - 80. Also, the following United States patents disclose various proposals for catheters: U.S. Pat. Nos. 88,695; 1,870,924; 1,922,084; 2,050,407; 2,175,726; 2,230,226; 2,259,488; 2,322,858; 2,559,281; 2,259,488; 2,343,579; 2,616,429; 2,642,874; 2,649,092; 2,693,191; 2,849,001; 2,854,983; 2,343,579; 2,915,058; and 3,799,172. None of the catheters disclosed in these patents, however, has been in widespread use, the Foley catheter having been the prototype of indwelling urethral catheters for the last 30 years, as previously mentioned.
It would be highly advantageous to provide a catheter in which there is no extra lumen to decrease urine drainage surface area, in which there is no balloon to cause the above mentioned problems with balloons, where no syringe is required, which is simpler to use than the Foley catheter, less expensive to manufacture, one in which the patient cannot injure himself, which is virtually fail-safe and fool-proof, in which the puddling phenomona is eliminated, and in which the expansion tip cannot be activated until the catheter is all the way into the bladder.